Electrochemical deposition of chromium core-shell nanostructures on H-Si(100): Evolution of spherical nanoparticles to uniform thin film without and with atop hexagonal microrods

Electrodeposition in Cr(VI) and Cr(III) aqueous electrolytes is found to produce, respectively, granular and spherical core-shell nanoparticles on H-terminated Si(100). For the granular nanoparticles obtained by electrodeposition in CrO3 and H2SO4 electrolyte solution, both the morphology and number density remain discernibly similar while the particle size increases with increasing charge transfer. In the CrCl3 electrolyte, evolution of the spherical nanoparticles to homogeneous Cr films without and with atop hexagonal microrods with increasing charge transfer is observed. The viability of producing a homogeneous Cr film on the Si substrate is therefore demonstrated. Both the granular Cr nanoparticles and the Cr film consist of predominantly Cr metallic core and Cr2O3 outer shell covered by surface CrO3, while the novel hexagonal microrods are made up of a metallic Cr core and a CrOOH shell.